Changelog generator

Changelog Generator

Tier: POWERFUL
Category: Engineering
Domain: Release Management / Documentation

Overview

Use this skill to produce consistent, auditable release notes from Conventional Commits. It separates commit parsing, semantic bump logic, and changelog rendering so teams can automate releases without losing editorial control.

Core Capabilities

• Parse commit messages using Conventional Commit rules
• Detect semantic bump (major, minor, patch) from commit stream
• Render Keep a Changelog sections (Added, Changed, Fixed, etc.)
• Generate release entries from git ranges or provided commit input
• Enforce commit format with a dedicated linter script
• Support CI integration via machine-readable JSON output

When to Use

• Before publishing a release tag
• During CI to generate release notes automatically
• During PR checks to block invalid commit message formats
• In monorepos where package changelogs require scoped filtering
• When converting raw git history into user-facing notes

Key Workflows

1. Generate Changelog Entry From Git

python3 scripts/generate_changelog.py \
  --from-tag v1.3.0 \
  --to-tag v1.4.0 \
  --next-version v1.4.0 \
  --format markdown

2. Generate Entry From stdin/File Input

git log v1.3.0..v1.4.0 --pretty=format:'%s' | \
  python3 scripts/generate_changelog.py --next-version v1.4.0 --format markdown

python3 scripts/generate_changelog.py --input commits.txt --next-version v1.4.0 --format json

3. Update CHANGELOG.md

python3 scripts/generate_changelog.py \
  --from-tag v1.3.0 \
  --to-tag HEAD \
  --next-version v1.4.0 \
  --write CHANGELOG.md

4. Compute the Next Version From Commits

When the user has not decided the next version, derive it instead of guessing:

git log v1.3.0..HEAD --oneline | \
  python3 scripts/version_bumper.py --current-version 1.3.0 --output-format json

Output JSON contains recommended_version, bump_type (major/minor/patch/none), and with --include-commands the exact git tag commands. Feed recommended_version into generate_changelog.py --next-version. Pre-releases: add --prerelease alpha|beta|rc. Input must be real git log --oneline output (hex hashes); a sample lives at assets/sample_git_log.txt.

5. Lint Commits Before Merge

python3 scripts/commit_linter.py --from-ref origin/main --to-ref HEAD --strict --format text

Or file/stdin:

python3 scripts/commit_linter.py --input commits.txt --strict
cat commits.txt | python3 scripts/commit_linter.py --format json

Conventional Commit Rules

Supported types:

• feat, fix, perf, refactor, docs, test, build, ci, chore
• security, deprecated, remove

Breaking changes:

• type(scope)!: summary
• Footer/body includes BREAKING CHANGE:

SemVer mapping:

• breaking -> major
• non-breaking feat -> minor
• all others -> patch

Script Interfaces

• python3 scripts/generate_changelog.py --help
  • Reads commits from git or stdin/--input
  • Renders markdown or JSON
  • Optional in-place changelog prepend
• python3 scripts/commit_linter.py --help
  • Validates commit format
  • Returns non-zero in --strict mode on violations

Common Pitfalls

1. Mixing merge commit messages with release commit parsing
2. Using vague commit summaries that cannot become release notes
3. Failing to include migration guidance for breaking changes
4. Treating docs/chore changes as user-facing features
5. Overwriting historical changelog sections instead of prepending

Best Practices

1. Keep commits small and intent-driven.
2. Scope commit messages (feat(api): ...) in multi-package repos.
3. Enforce linter checks in PR pipelines.
4. Review generated markdown before publishing.
5. Tag releases only after changelog generation succeeds.
6. Keep an [Unreleased] section for manual curation when needed.

Hotfix Severity & SLAs

When a release goes wrong, classify before acting (full procedures in references/hotfix-procedures.md):

Severity	Definition	SLA	Approval
P0 — Critical	Outage, data loss, exploited vulnerability	Fix deployed ≤ 2h; emergency deploy bypasses normal gates	Engineering Lead + On-call Manager
P1 — High	Major feature broken, significant user impact	Fix deployed ≤ 24h; expedited review	Engineering Lead + Product Manager
P2 — Medium	Minor issues, limited impact	Next release cycle	Standard PR review

Hotfix branch comes from the last stable tag, contains the minimal fix only, and gets its own patch-bump changelog entry via the workflow above.

Rollback Triggers

Pre-commit to these thresholds before tagging; roll back when any fires:

Trigger	Threshold
Error rate spike	> 2x baseline within 30 min
Performance degradation	> 50% latency increase
Feature failure	Core functionality broken
Security incident	Vulnerability being exploited
Data corruption	Database integrity compromised

Prefer feature-flag disable over code rollback; database rollbacks only for non-destructive migrations (forward-only migrations preferred). See references/hotfix-procedures.md.

References

• references/ci-integration.md
• references/changelog-formatting-guide.md
• references/monorepo-strategy.md
• references/hotfix-procedures.md
• README.md

Release Governance

Use this release flow for predictability:

1. Lint commit history for target release range.
2. Generate changelog draft from commits.
3. Manually adjust wording for customer clarity.
4. Validate semver bump recommendation.
5. Tag release only after changelog is approved.

Output Quality Checks

• Each bullet is user-meaningful, not implementation noise.
• Breaking changes include migration action.
• Security fixes are isolated in Security section.
• Sections with no entries are omitted.
• Duplicate bullets across sections are removed.

CI Policy

• Run commit_linter.py --strict on all PRs.
• Block merge on invalid conventional commits.
• Auto-generate draft release notes on tag push.
• Require human approval before writing into CHANGELOG.md on main branch.

Monorepo Guidance

• Prefer commit scopes aligned to package names.
• Filter commit stream by scope for package-specific releases.
• Keep infra-wide changes in root changelog.
• Store package changelogs near package roots for ownership clarity.

Failure Handling

• If no valid conventional commits found: fail early, do not generate misleading empty notes.
• If git range invalid: surface explicit range in error output.
• If write target missing: create safe changelog header scaffolding.